Breaking

Anthropic Releases Claude Sonnet 5.5 for Faster Coding and Knowledge Work

September 28, 2026 at 17:41 EDT

Foundation Models
AI Agents
Software Dev & Coding

Anthropic released Claude Sonnet 5.5 on September 28, positioning the model as a faster, lower-cost complement to Claude Opus 5.5 for coding agents and everyday knowledge work. The company says the new Sonnet model is available across its platforms, including Amazon Web Services, Google Cloud and Microsoft Azure, with the Claude Platform model ID claude-sonnet-5-5.

Sep. 28, 2026 · Anthropic

Claude Sonnet 5.5 moves into the coding lane

The new Sonnet model is positioned as a faster, lower-cost complement to Opus 5.5 for agentic coding and everyday knowledge work.

70.6%

Terminal-Bench 4.0 score

Input price per 1M tokens

30%+

Faster output than Sonnet 5

Coding benchmark jump

10.3%Sonnet 5

70.6%Sonnet 5.5

66.4%Opus 5.5

On Terminal-Bench 4.0, Sonnet 5.5 moves from the prior Sonnet tier to a score above Opus 5.5's reported Xhigh result.

Why teams may use it

Lower per-token pricing, faster output and fewer tokens per task make Sonnet 5.5 attractive for well-scoped implementation, bug fixing and workplace deliverables.

Where Opus still matters

Anthropic still positions Opus 5.5 as stronger for complex, open-ended work requiring sustained judgment, especially at higher effort levels.

Developer routing logic

Plan with Opus→Implement with Sonnet→Tune effort by task

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